Hi @MuRF,
It would be great to know the exact packet that causes the issue but, unless its a broadcast or in some cases multicast packet, it will be only between Google speaker and the modem meaning your PC won't see it so tldr unfortunately Wireshark'ing on your PC won't cut it.
At the moment we don't have a google speaker in the office. We ordered one and as soon as it arrives we will set it up. We could have a session in AEST daytime at the time of your choosing. However, It might be best to wait until we setup the speaker ourselves locally, since we will have full access of the unit it should be very easy to diagnose and fix.
Thanks